Engineers present 25-year water asset management plan; recommends about $30 million in pipe work

The township received a draft water asset management plan and a near-complete water reliability study during a public presentation at the Grosse Ile DPS Commission meeting. Maria Sedka, an engineer with Fishbeck, summarized an inventory of the water system, condition and criticality ratings used to prioritize replacement, and a capital-improvement plan covering roughly 20–25 years.

The plan matters because it compiles an asset inventory and condition assessment required by EGLE, ranks assets by probability and consequence of failure, and translates that analysis into a prioritized replacement list and cost estimate. The presentation focused on the age, material and size of pipes, the system’s hydraulic performance for fire flows, and how these factors drive project sequencing.

Sedka said the team combined three information sources to build the capital-improvement plan: the condition-based probability-of-failure scoring, the water reliability (hydraulic) modeling that shows where upsizing is needed for pressure and fire flow, and local operations knowledge from township staff. She said the GIS-backed inventory links all record drawings to mapped mains, valves and hydrants and makes that information available for field crews.

The inventory totals Sedka described included 605 gate valves, 681 hydrants and about 398,000 feet of water main. She said the system still contains a substantial amount of 6-inch cast-iron mains, much of which dates from the 1920s–1940s; those segments show high probability of failure but lower system consequence because they serve smaller areas. Conversely, larger transmission mains and the two connections from the mainland scored high in consequence of failure because they serve broad areas and are hard to access.

The plan uses EGLE’s business-risk-exposure (BRE) approach (probability times consequence, scored 1–25) to prioritize projects. Sedka said the township currently has no high BRE items (16–25) because the worst-condition pipes are typically small-diameter lines with limited system impact; nonetheless, she urged replacement of many old 6-inch cast-iron segments over time. The reliability model flagged portions that need upsizing (8- to 12-inch replacements) to meet recommended fire-flow contours; the presentation noted a local target of about 2,000 gallons per minute where possible.

Sedka said the team generated an Excel inventory that lists each GIS segment, material, installation decade and an engineering replacement-cost estimate. She gave typical useful-life benchmarks used in the analysis: PVC and HDPE (plastic) at about 50 years and ductile iron at about 75 years, noting industry benchmarks can change as longer field records accumulate.

The draft capital plan shown to the commission recommends replacing a first tranche of segments identified across the system (42 GIS segments called out in the presentation) and estimated a minimum set of replacements totaling roughly $30,000,000 in 2025 dollars over the 20–25 year horizon. Sedka emphasized the number represents a planning-level estimate using unit lengths and diameter-based unit costs and does not include detailed pavement restoration or site-specific construction complexities.

Township staff and commissioners discussed sequencing and funding. Derek (staff member) said the next steps are to finalize the draft report, provide the commission and staff the Excel inventory to allow prioritization, and prepare a funding strategy in the coming 3–6 months that balances bonding, pay-as-you-go capital, and timing of bond maturities. Sedka said the draft water reliability study should be finalized within a few weeks and will be submitted to EGLE with the asset-management report, as EGLE expects periodic updates.

Commissioners asked for clarifications that were recorded in the meeting: how probability-of-failure scoring is derived (age/remaining useful life, hydraulic c-factor from modeling, and historic break frequency), the GIS positional tolerance (“down to inches” in the linked GIS as presented), and whether recommended pipe materials and installation methods affect per-foot cost. Staff and Sedka confirmed variances in installation method and site constraints (railroad, creeks, tunneling) can affect both material choice and unit cost.

Sedka and staff noted a separate but related item: the plan identified many lead service lines. The meeting record indicates an inventory was completed and the township has approximately 403 lead service lines to replace; the draft budget proposes replacing about 10 in the next fiscal year at an estimated $5,000–$7,000 per service line, with the township aiming to replace as many as the budget allows over the next several years.

The presentation closed with a timetable: the consultant will finalize the draft report for staff review, the township will submit the document to EGLE, and EGLE appears likely to request an update every several years (presenters said a five-year review cadence is becoming common). Derek said staff will develop funding scenarios and return to the commission with options that try to minimize consumer rate impacts while addressing priorities.

The commission did not adopt or vote on policy at the presentation; the plan was presented for review and next-step planning.